The aortic smooth muscle cell in culture has served as an excellent homogeneous single cell system to study the metabolism of dolichols and their intermediary role in the assembly of membrane glycoproteins. We have established that dolichols share common biosynthetic steps with cholesterol since they require mevalonate for their synthesis. In their phosphorylated form the dolichols serve as acceptors and donors of saccharide units, and both functions implicate them as obligatory intermediates in the synthesis of glycoproteins. We have focused our investigations on these two functions and in addition determined in part the structure of the oligosaccharide units as they become assembled on dolichol. Specific glycosyl transferases utilize a combination of nucleotide sugars and dolichyl-monosaccharides as glycose donors to assemble dolichyl-PP-oligosaccharides. The latter are in turn transferred in toto onto nascent peptide chains on membrane bound polysomes and the resulting glycoproteins appear later on the cell surface. These oligosaccharides contain 10 man, 2 Glc and 2 GlcNAc residues which after a series of enzymatic and Smith degradations are deduced to consist of a 4 GlcNAc core structure to which 5 peripheral alpha mannoside residues are attached. The glucose residues likely function as recognition points for specific endoglycosidases concerned with processing and maturation of some of these units into sialic acid containing heterosaccharide units as found in membrane glycoproteins. The relationship of dolichol bound and membrane protein bound carbohydrate units is presently under scrutiny particularly as relates to the suggestion that the lipid bound saccharide undergoes substantial processing after it becomes bound to protein.